[Hexaamminecobalt(III)] Dichloride Permanganate-Structural Features and Heat-Induced Transformations into (Co-II,Mn-II)(Co-III,Mn-III)(2)O-4 Spinels

We synthesized and characterized (IR, Raman, UV, SXRD) hexaamminecobalt(III) dichloride permanganate, [Co(NH3)(6)]Cl-2(MnO4) (compound 1) as the precursor of Co-Mn-spinel composites with atomic ratios of Co:Mn = 1:1 and 1:3. The 3D-hydrogen bond network includes N-H center dot center dot center dot O-Mn and N-H center dot center dot center dot Cl interactions responsible for solid-phase redox reactions between the permanganate anions and ammonia ligands. The temperature-limited thermal decomposition of compound 1 under the temperature of boiling toluene (110 degrees C) resulted in the formation of (NH4)(4)Co2Mn6O12. which contains a todorokite-like manganese oxide network ((Mn4Mn2O1210-)-Mn-II-O-III). The heat treatment products of compounds 1 and [Co(NH3)(5)Cl](MnO4)(2) (2) synthesized previously at 500 degrees C were a cubic and a tetragonal spinel with Co1.5Mn1.5O4 and CoMn2O4 composition, respectively. The heating of the decomposition product of compounds 1 and 2 that formed under refluxing toluene (a mixture with an atomic ratio of Co:Mn = 1:1 and 1:2) and after aqueous leaching ((NH4)(4)Co2Mn6O12, 1:3 Co:Mn atomic ratio in both cases) at 500 degrees C resulted in tetragonal Co0.75Mn2.25O4 spinels. The Co1.5Mn1.5O4 prepared from compound 1 at 500 degrees C during the solid-phase decomposition catalyzes the degradation of Congo red with UV light. The decomposition rate of the dye was found to be nine times faster than in the presence of the tetragonal CoMn2O4 spinel prepared in the solid-phase decomposition of compound 2. The todorokite-like intermediate prepared from compound 1 under N-2 at 115 degrees C resulted in a 54 times faster degradation of Congo red, which is a great deal faster than the same todorokite-like phase that formed from compound 2 under N-2.